The establishment of low-grade microfilaremias in Taiwan macaques during the past year will allow for transmission studies of this parasite to other species of macaque monkeys. It is proposed that serial passage of this parasite in monkeys will result in enhancement of infection and the production in monkeys of microfilaremias that will allow routine maintenance of the infection in the laboratory. Further work defining the immune response in filaral infections will be carried out, primarily using the Brugia pahangi jird (Meriones unguiculatus) model. It is proposed to make extensive use of an inbred (MON/Tum) strain of jird to determine the protective value of transferred immune components and their effects on established filarial infections. Exploitation of mice as hosts for B. pahangi infection will be continued since the use of genetically defined hosts will enhance immune studies and allow for comparison with other parasitic infections that are now routinely studied in various strains of mice. Finally, studies on the pathology of the spleen in jirds infected with B. pahangi and ultrastructure of Wuchereria bancrofti will be completed. BIBLIOGRAPHIC REFERENCES: Portaro, J.K., J.C. Kowalski, C. Howell and L.R. Ash 1977. Use of lymphocyte transformation for the detection of filarial infections. J. Parasitol. 63: 172-174. Karavodin, L.M. and L.R. Ash 1977. Weak mixed lymphocyte culture response in the Mongolian gerbil (Meriones unguiculatus). Lab. Animal Sci., In Press.